Systematics of charge-pickup reactions by GeV/nucleon heavy nuclei

Abstract

We have measured cross sections for inclusive reactions in which 1.7 GeV/N $^{56}\mathrm{Fe}$, 1.46 GeV/N $^{84}\mathrm{Kr}$, 1.28 GeV/N $^{139}\mathrm{La}$, and 0.8 GeV/N $^{197}\mathrm{Au}$ increased in charge by one unit. Combining these results with data on charge pickup by $^{12}\mathrm{C}$, $^{18}\mathrm{O}$, and $^{20}\mathrm{Ne}$ projectiles, we find that the cross section for charge pickup by \ensuremath{\sim}GeV/nucleon projectiles is generally given to within a factor of 2 by the expression ${\ensuremath{\sigma}}_{\ensuremath{\Delta}Z=+1}$=1.7\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}4}$ ${\ensuremath{\gamma}}_{\mathrm{PT}}$${A}_{P}^{2}$ (in mb), where ${\ensuremath{\gamma}}_{\mathrm{PT}}$=${A}_{P}^{1/3}$ +${A}_{T}^{1/3}$-1.0. This expression, with roles of projectile and target interchanged, equally well fits cross sections for (p,xn) reactions at GeV energies when summed over x. The factor ${\ensuremath{\gamma}}_{\mathrm{PT}}$ implies peripheral collisions; the dependence on ${A}_{P}^{2}$ is the steepest ever reported for a nuclear process.